覆膜开孔条件下植物混掺对土壤蒸发的影响

为探讨覆膜开孔条件下植物混掺对土壤蒸发规律的影响,测定了不同植物混掺物(玉米叶和玉米芯)、土壤容重(1.35 g·cm~(~(-3))和1.40 g·cm~(~(-3)))、膜孔直径(2、4 cm和6 cm)在植物混掺比例为1%时的土壤水分扩散率、土壤水分特征曲线和土壤累计蒸发量。结果表明:相同土壤容重条件下的土壤水分扩散率呈现1%玉米芯纯土1%玉米叶;纯土及同种植物混掺物相同混掺比例处理中,土壤水分扩散率均表现为土壤容重1.35 g·cm~(~(-3))处理高于1.40 g·cm~(~(-3))处理;低吸力阶段,各处理土壤含水率下降较快,土壤水分特征曲线较陡,随土壤水吸力逐渐增大,曲线呈现变缓趋势;在相同土壤水吸力下,各添加植物混掺物处理的土壤含水率均高于纯土处理;不同土壤容重的土壤累计蒸发量呈现1%玉米芯1%玉米叶纯土;各处理土壤累计蒸发量随膜孔直径变化呈现出6 cm4 cm2 cm的规律;相同膜孔直径条件下,各处理土壤累计蒸发量均表现为土壤容重为1.40 g·cm~(~(-3))的处理高于1.35 g·cm~(~(-3))处理。     

吉林西部苏打盐碱土在不同添加物下水分入渗特性

依据土壤水动力学理论,基于室内一维土柱入渗试验,选用稻壳、玉米秸秆、河沙3种材料作为添加物,分别将添加物以不同掺量与土壤均匀混合对苏打盐碱土进行入渗试验,从累计入渗量、入渗速率、湿润锋运移距离等方面研究苏打盐碱土在不同添加物及不同掺量下水分的入渗特性。结果表明:对照组土壤入渗量为3 mm·d~(-1),混掺1%稻壳、玉米秸秆时土壤入渗量分别为7.08、7.37 mm·d~(-1),混掺3%稻壳、玉米秸秆时土壤入渗量分别为18.9、23.07 mm·d~(-1),混掺5%稻壳、玉米秸秆时土壤入渗量分别为21.17、28.5 mm·d~(-1)。对照组土壤稳定入渗速率为0.04 mm·h~(-1),混掺1%、3%、5%稻壳土壤稳定入渗速率分别为0.17、0.55、0.60 mm·h~(-1),混掺1%、3%、5%玉米秸秆土壤稳定入渗速率分别为0.25、0.70、1.00 mm·h~(-1),混掺25%、40%、55%河沙土壤稳定入渗速率为0.08、0.09、0.10 mm·h~(-1)。对照组土壤湿润锋运移距离为4.9 cm,混掺1%、3%、5%稻壳土壤湿润锋运移距离分别为10.1、30、38.3 cm,混掺1%、3%、5%玉米秸秆土壤湿润锋运移距离分别为11.6、32、47 cm,混掺25%、40%、55%河沙土壤湿润锋运移距离分别为6.5、7.8、9 cm。混掺5%玉米秸秆可以大幅度增加土壤累计入渗量,提高水分入渗速率,浸润范围可以到达作物根系。因此选用5%玉米秸秆掺量与土壤混掺,可提升吉林西部苏打盐碱土入渗效果,有利于综合提高土壤水分入渗和保水性能。     

毛乌素沙地复配土壤水分特征曲线模型筛选研究

针对国家增加可利用土地、降低水土流失的需求,利用复配土壤对风沙土进行改良,是实现毛乌素沙地治理、区域生态修复的重要手段。测定不同复配比例土壤的水力学性质,并进一步筛选出合适复配土壤使用的水分特征曲线模型,运用高速离心机法测定对复配土壤水分特征曲线,环刀法测定复配土饱和导水率,并对比不同水分特征曲线模型对于不同比例复配土壤的模拟效果。研究表明:相同土壤水吸力下,添加砒砂岩处理的土壤含水率均高于纯风沙土处理;复配比例中砒砂岩含量越高,土壤保水性越高;当砒砂岩与风沙土复配比例高于5:1后,土壤水分特征曲线与纯砒砂岩差异不大;低吸力阶段,砒砂岩的添加减少了土壤中大孔隙的比例,而在中高吸力阶段,砒砂岩的添加增大了土壤中小孔隙的比例,进而提高土体的持水能力。模型适宜性分析结果表明,能够适配各处理的非饱和导水率模式最优模型为van Genuchten模型;砒砂岩与沙复配比例高于1:5后,Gardner模型的相关系数从0.9473上升至0.9929,残差平方和0.041降低至0.010,模拟效果逐渐超越van Genuchten模型,间接推求公式Arya-Paris模型物理概念明确,但影响因素过多,相较经验公式拟合效果不佳。     

陶瓷空心微珠掺量对沙质土壤持水性的影响

特殊的地理位置与特定的自然环境，加之人类的生产活动影响导致部分地区土壤沙化趋于严重，沙质土壤因其特殊的质地，其持水能力急剧下降，干旱区植物难以生存，区域荒漠化加重，对生态环境造成巨大破坏。为恢复沙质土壤地区的生态环境，引入新型保水性多孔材料-陶瓷空心微珠对沙质土壤持水能力进行提升。利用土壤高速离心机模拟含陶瓷空心微珠沙质土壤的脱湿过程，结合Van Genuchten模型定量分析陶瓷空心微珠对土壤水分特征曲线及其参数的影响。利用土壤三相仪测定陶瓷空心微珠掺量对土壤三相变化的影响。结果表明：随陶瓷空心微珠掺量增加，土壤水分特征曲线形状斜率变化减缓，持水曲线减湿率降低，曲线形状参数n降低；随掺量增加土壤饱和含水率升高，提升效果随掺量增加逐渐减弱，随掺量增加土壤固相比降低，土壤液相与气相比升高，变化效果随掺量增加逐渐减弱。土壤水分特征曲线与土壤三相比测定结果表明沙质土壤持水性提升与陶瓷空心微珠掺量呈正相关，其提升效果随掺量增加而减弱。     

不同改良方法对盐碱土壤水盐运移效果的影响

以取自山东省东营市的中度盐碱土为研究对象，为探究表层（0~20 cm）掺沙和掺生物炭处理对黄河三角洲地区盐碱土的改良效果，在室内进行了垂直一维积水入渗试验，分别研究两种方法对土壤水分入渗、土壤剖面含水率和含盐量的影响。试验土壤为中度盐碱土(含盐量2.381 g·kg^-1)，试验共设置7个处理，分别是：CK(掺沙或生物炭0%)、S1(掺沙5%)、S2(掺沙10%)、S3(掺沙20%)、C1(掺生物炭0.5%)、C2(掺生物炭1%)、C3(掺生物炭2%)。结果表明：在相同入渗情况下，表层（0~20 cm）掺沙、生物炭均能提高盐渍化土壤中水分入渗效果，掺加生物炭显著提高添加层的蓄水能力，掺沙显著提高掺沙层以下土壤含水率，在土层20~40 cm中，掺沙处理平均土壤含水率比掺生物炭处理提高1.37%；不同改良剂处理下，掺沙更有利于盐碱化土壤脱盐，20%掺沙处理平均脱盐率比掺生物炭处理提高5.26%~13.80%，脱盐区深度增加2.35%~3.92%，达标脱盐区深度增加1.70%~3.00%。根据河沙和生物炭在室内一维垂直积水入渗试验结果来看，土壤表层掺沙能有效解决黄河三角洲地区盐碱化土壤问题，改善土壤水盐分布，为作物生长提供良好的生长环境。     

保墒灌溉对夏玉米地土壤水分迁移转化的影响

设置地膜覆盖、秸秆覆盖和PAM化学保水剂3种保墒处理,研究不同保墒灌溉下夏玉米地土壤水分沿剖面变化规律与夏玉米整个生育期耗水规律的异同.试验结果表明:在灌溉或非灌溉条件下,各保墒处理的土壤含水量在0～150 cm均高于相同条件下的对照,且各保墒灌溉对土壤储水量的提高,随着灌溉水量的增加而增加.试验结果还表明:地膜覆盖、...     

基于HYDRUS-2D的滨海地区膜下滴灌土壤水盐运移模拟研究

以春玉米“郑单958”为供试作物，采用膜下滴灌灌水方式，设定2种不同灌水定额，分别是单次灌水定额20 mm和10 mm，测定试验区土壤水分、盐分含量，利用HYDRUS-2D模型对土壤水盐运移进行模拟，将模拟值与实测值进行对比分析，探究滨海地区盐碱化土壤水盐运移规律。结果表明：滴灌过程中，水平方向土壤盐分由膜下向膜边运移，膜下土壤淋洗效果好于膜边；竖直方向0~20 cm土壤水分、盐分变化幅度最大，土壤含盐量降低16.1%，淋洗效果明显；下层土壤盐分淋洗效果一般，土壤含盐量降低值仅为9.6%。土壤水分重分布过程中，0~20 cm土层土壤含水率和含盐量变化幅度比20~60 cm土层大。0~20 cm、20~40 cm和40~60 cm土层高灌水定额（20 mm）处理对土壤盐分的抑制作用分别比低灌水定额（10 mm）处理高26%、11%、19%，并且高灌水定额滴灌将土壤盐分淋洗到60 cm土层以下，而低灌水定额滴灌未能将土壤盐分淋洗到60cm土层以下。HYDRUS-2D模拟得到的土壤含水率与含盐量和实测值基本吻合，模型可靠。     

不同耕作措施对旱地玉米生长环境及产量的影响

采用田间定位试验,研究了羊粪4 m3+深耕30~35 cm(MP3)、羊粪4 m3+深耕20~25 cm(MP2)、羊粪4 m3+旋耕10~15 cm(MP1)、深耕30~35 cm(P3)、深耕20~25 cm(P2)、旋耕10~15 cm(P1)6种耕作措施下旱地玉米土壤温度、土壤水分、土壤呼吸速率及产量的变化。结果表明:采用不同耕作措施均能有效促进旱地玉米生长,与传统耕作方式(P1)相比,MP3、P3处理的土壤体积含水量分别提高了39.00%、32.44%;MP3处理下土壤温度显著高于传统耕作0.94℃;随着旱地玉米生育期的推进,土壤呼吸速率峰值出现在6月底,不同耕作方式下土壤呼吸速率较传统耕作提高了0.68~1.26倍;深耕处理、深耕+羊粪处理的旱地玉米产量均显著高于传统耕作,其增幅在11.94%~36.51%。通过3年试验比较,羊粪4 m3+深耕30~35 cm、羊粪4 m3+深耕20~25 cm、深耕30~35 cm效果较好。     

保水剂对半干旱区砂壤土水分运动的影响试验研究

采用室内土柱试验,研究了BJ2101XM型保水剂3种施用量及沟施和混施的方法对典型半干旱砂性土壤的入渗和蒸发的影响。结果表明:施用后,入渗速率最大降至对照的0.77(混施)和0.89(沟施);相同初始含水率下,连续蒸发下,土壤含水率均高于对照,其中混施6kg/亩的各层含水率是对照的1.3-39倍,其15cm处提高了42%;混施比沟施减少了6-25%的土壤蒸发量。     

辽西半干旱区秋覆膜对土壤水分及玉米水分利用效率的影响

秋覆膜技术是传统地膜覆盖栽培技术的创新和延伸。为了探明秋季覆膜对土壤水分及玉米水分利用效率的影响,2014年在农业部阜新农业环境与耕地保育科学观测实验站,设置常规裸地种植(T1)、传统春覆膜(T2)、秋覆膜(T3)以及秋覆膜配施秸秆(T4)四种处理,研究了不同覆膜处理对土壤蓄水量、水分剖面分布、春玉米产量及水分利用效率的影响。结果表明,两种秋覆膜处理可实现对土壤水分的跨季节调控,播前土壤蓄水量比裸地增加35.44%和23.09%,比春覆膜增加40.79%和27.95%,整个生育期土壤蓄水量较裸地增加30.70%和20.10%,较春覆膜增加37.77%和26.59%。两种秋覆膜处理的剖面土壤水分在各生育时期均较为充足;春覆膜处理土壤含水率随土层深度变化剧烈,下层土壤水分严重缺失。秋覆膜处理可显著增加玉米产量,较裸地和春覆膜处理平均增产13.26%和13.52%,单株粒重增加是秋覆膜提高玉米产量的主要原因。秋覆膜T3处理可充分利用作物生育期降水,与T1、T2、T4处理相比,水分利用效率显著提高8.24%、9.74%和8.83%。     

基于介电频谱特征参数的红壤干旱指标评价研究

为获取红壤含水量对电磁波介电频谱的响应特征，探讨介电频谱特征参数作为红壤干旱评价指标的可行性，以红壤为研究对象，开展不同体积含水量红壤的频域介电谱（FDS）试验，提取介电谱特征曲线积分值，分析介电频谱特征参数与体积含水量的相关性，结合国家《农业干旱等级》标准提出基于介电频谱特征参数的红壤干旱评价指标。结果表明：红壤介电常数实部和虚部均随着介电频谱频率的增大而逐渐减小，两者与体积含水量均呈正相关关系；介电损耗因数随频率变化具有波动性，且体积含水量越小波动性越强，总体呈现出先减小后增大的趋势；通过最小二乘法拟合得到介电频谱特征参数与体积含水量的量化关系，采用细菌觅食算法确定最优的模型系数，拟合精度均大于0.95；基于介电谱特征参数建立红壤干旱指标评价模型，预测值与标准值之间的误差均为±1%左右。该模型能有效地评价红壤干旱程度，可为红壤区域性农业干旱调查、评估及预警提供参考指标。     

Polychlorinated biphenyl contamination of areas surrounding two transformer salvage companies, Colman, South Dakota--September 1977

Soil, corn plants, and foliage from areas surrounding two electrical salvage companies involved in reconditioning old transformers had unusually high levels of polychlorinated biphenyls (PCBs). Levels decreased as distance from the factories increased. PCBs were dispersed into the air through incineration of waste oils; water and soil contamination was caused by runoff from the factories. PCBs found in the contaminated areas closely resembled Aroclor 1260 as did the PCBs in the waste oil, whereas PCBs in other areas were more similar to Aroclor 1254. PCBs on surface soils taken from an unplowed pasture near the factories also resembled Aroclor 1260, whereas samples taken from depths of 2-4 inches showed degradation of some PCB isomers. PCB concentrations in corn cobs and kernels were < 0.05 ppm, whereas leaves contained PCB levels of up to 2.2 ppm. PCB levels in earthworms and small rodents collected near the factories were considerably higher than levels in the same types of animals collected from other areas.     

Relationships Between Verticillium dahliae Inoculum Density and Wilt Incidence, Severity, and Growth of Cauliflower

ABSTRACT Microplot and field experiments were conducted to evaluate the effects of inoculum density on Verticillium wilt and cauliflower growth. Soil containing Verticillium dahliae microsclerotia was mixed with various proportions of fumigated soil to establish different inoculum densities (fumigated soil was used as the noninfested control). Seven inoculum density treatments replicated four times were established, and the treatments were arranged in a randomized complete block design. Soil was collected from each microplot immediately after soil infestation for V. dahliae assay by plating onto sodium polypectate agar (NP-10) selective medium using the Anderson sampler technique. Five-week-old cauliflower was transplanted into two beds within each 1.2- by 1.2-m microplot. At the same time, several extra plants were also transplanted at the edge of each bed for destructive sampling to examine the disease onset (vascular discoloration) after planting. Cauliflower plants were monitored for Verticillium wilt development. Stomatal resistance in two visually healthy upper and two lower, diseased leaves in each microplot was measured three times at weekly intervals after initial wilt symptoms occurred. At maturity, all plants were uprooted, washed free of soil, and wilt incidence and severity, plant height, number of leaves, and dry weights of leaves and roots were determined. The higher the inoculum density, the earlier was disease onset. A density of 4 microsclerotia per g of dry soil caused 16% wilt incidence, but about 10 microsclerotia per g of soil caused 50% wilt incidence. Both wilt incidence and severity increased with increasing inoculum density up to about 20 microsclerotia per g of soil, and additional inoculum did not result in significantly higher disease incidence and severity. A negative exponential model described the disease relationships to inoculum levels under both microplot and field conditions. Stomatal resistance of diseased leaves was significantly higher at higher inoculum densities; in healthy leaves, however, no treatment differences occurred. The height, number of leaves, and dry weights of leaves and roots of plants in the fumigated control were significantly higher than in infested treatments, but the effects of inoculum density treatments were variable between years. Timing of cauliflower infection, crop physiological processes related to hydraulic conductance, and wilt intensity (incidence and severity) were thus affected by the inoculum density. Verticillium wilt management methods used in cauliflower should reduce inoculum density to less than four micro-sclerotia per g of soil to produce crops with the fewest number of infected plants.     

Partitioning evapotranspiration of desert plants under different water regimes in the inland Heihe River Basin,Northwestern China

Plant transpiration (T), soil evaporation (E), and the proportion of evaporation in evapotranspiration (ET), and their patterns of change were analyzed in a desert habitat along the middle and lower reaches of the Heihe River Basin, Gansu Province, China. Typical desert plants with different life forms were selected and small lysimeter observations were conducted; various species were measured under two soil water regimes using 50% (FC 50%) and 20% (FC 20%) of field capacity in 2 years. Under the FC 50% treatment the observed ratio of T to ET of desert plants was less than one-third, making the ratio of E to ET greater than two-thirds; the proportion of T to ET of desert plants increased to above 40%, and that of E declined to below 60% under the FC 20% treatment. The lowest T of desert plants was 130–140 mm based on the plant crown projection area. The characteristic coefficient of ET of desert plants was twice that of the characteristic coefficient of transpiration. This study found that when ET was measured for the same desert plant species growing in different regions, the ET differed significantly (P < 0.05) under the same water regimes; when comparing different plant species in the same region no obvious differences in the transpiration water requirement and ET were observed. The proportion of T in ET increased significantly and E in ET decreased markedly (P < 0.05), if the soil moisture content declined to where the plants experienced water stress.     

可降解膜覆盖对土壤水分蒸发特性的影响

于2017年5—11月开展室内土柱蒸发试验,研究了5种覆盖层(无膜:CK;普通地膜:PE;A型完全生物降解地膜:BD1;B型完全生物降解地膜:BD2;C型生物降解地膜:BD3)在2种辐射方式(连续、间断)、3种光照环境(近光、中间光、远光)下对土壤水分蒸发特性的影响。结果表明:红外灯光连续和间断辐射方式下的各处理累积蒸发量曲线分别呈对数形和震荡波形。2种辐射方式下,各阶段蒸发量的变化关系都是近光中间光远光,且近光、中间光条件下的累积蒸发量较远光条件下分别高72%、50%(连续辐射)和70.5%、48.9%(间断辐射)。同样,连续和间断辐射方式下,与CK相比PE、BD1、BD2、BD3处理的抑蒸率分别为32.5%、16.51%、14.34%、16.35%和26.74%、16.69%、15.74%、17.18%。综合分析来看,覆膜可有效减小土壤水分蒸发,同覆盖层对土壤累积蒸发的抑制作用由大到小排列为:PEBD2BD1BD3CK。在相同的辐射情况下,B型完全生物降解膜处理的累积蒸发量Rose模型的拟合效果优于其他处理。     

不同灌溉模式下氮肥水平对水稻生物学特性及水分利用效率的影响

为了研究不同灌溉模式下氮肥水平对水稻生物学特性及水分利用效率的影响,以两优培九为材料,设计3种不同的灌溉模式（常规灌溉、干湿交替灌溉和厢沟灌溉,分别记作W1,W2,W3）和4种不同氮肥水平（0,90,180,270 kg/hm2,分别记作F0,F1,F2,F3）的大田试验。结果表明：与W1处理相比,W2和W3处理水稻灌...     

容重及含水率对土壤电导率的影响研究

土壤电导率能够间接反映田间养分或盐分含量,通过监测土壤电导率可以掌握土壤养分或盐分运移和利用情况。本文通过2种土壤容重、5种含水率条件下土柱入渗试验,利用5TE传感器对土壤体积含水率、体积电导率、温度等参数进行连续监测,分析容重及含水率对土壤电导率的影响。结果表明：在入渗过程中,含水率和电导率均先增大后逐渐减小,最后趋于平缓;电导率开始减小的时间较含水率开始减小的时间略有提前;当体积含水率一定时,孔隙水电导率随体积电导率的增加基本呈线性增加;随含水率的增大,孔隙水电导率随体积水电导率增大的速率变慢;当体积电导率一定时,随着含水率的增加,孔隙水电导率逐渐减小,容重为1.35 g·cm^-3时减幅为9.52%～55.51%,容重为1.3 g·cm^-3时减幅为9.72%～54.62%;孔隙水电导率一定时,体积电导率随含水率的增加而增大,容重为1.35 g·cm^-3时增幅为10.51%～124.75%,容重为1.3 g·cm^-3时增幅为10.76%～120.35%。对于2种容重情况,相同含水率下孔隙水电导率与...     

黄土丘陵区雨养梨枣树生长对初始土壤含水率的响应

以6年生矮化密植梨枣树(Ziziphus jujuba Mill.)为试材,在雨养条件下,设置4种不同初始土壤体积含水率水平(1区,15.17%;2区,14.33%;3区,11.34%;4区,8.61%),测定并分析土壤水分变化、枣树生长、枣树耗水及其产量。结果表明:在雨养条件下,随着时间的推进,4个小区的土壤体积含水率不断接近,由最初的有显著差异变为没有显著差异;梨枣林地在低土壤水分情况下,可以通过自然降雨修复干层;4个小区的生物量和产量都是随着初始土壤含水率的减小在减小,且小区之间产量差异显著;4种初始土壤水分条件下,4个小区获得的产量分别为21 744.9、18 648.0、12 354.3 kg·hm~(-2)和6 660.0 kg·hm~(-2),说明即使在初始土壤水分亏缺情况下,在平水年也可以得到一定的产量;高度为0.9~1.2 m,冠幅为0.5~0.9 m的梨枣树,产量却达到最高21 744.9 kg·hm~(-2),说明梨枣获得高产不需要高大的树体,所以矮化密植具有很大潜力。     

Effects of mixed-based biochar on water infiltration and evaporation in aeolian sand soil

Aeolian sandy soil in mining areas exhibits intense evaporation and poor water retention capacity. This study was designed to find a suitable biochar application method to improve soil water infiltration and minimize soil water evaporation for aeolian sand soil. Using the indoor soil column method, we studied the effects of three application patterns (A (0-20 cm was a mixed sample of mixed-based biochar and soil), B (0-10 cm was a mixed sample of mixed-based biochar and soil and 10-20 cm was soil), and C (0-10 cm was soil and 10-20 cm was a mixed sample of mixed-based biochar and soil)), four application amounts (0% (control, CK), 1%, 2%, and 4% of mixed-based biochar in dry soil), and two particle sizes (0.05-0.25 mm (S1) and <0.05 mm (S2)) of mixed-based biochar on water infiltration and evaporation of aeolian sandy soil. We separately used five infiltration models (the Philip, Kostiakov, Horton, USDA-NRCS (United States Department of Agriculture-Natural Resources Conservation Service), and Kostiakov-Lewis models) to fit cumulative infiltration and time. Compared with CK, the application of mixed-based biochar significantly reduced cumulative soil water infiltration. Under application patterns A, B, and C, the higher the application amount and the finer the particle size were, the lower the migration speed of the wetting front. With the same application amount, cumulative soil water infiltration under application pattern A was the lowest. Taking infiltration for 10 min as an example, the reductions of cumulative soil water infiltration under the treatments of A2%_(S2), A4%_(S1), A4%_(S2), A1%_(S1), C2%_(S1), and B1%_(S1) were higher than 30%, which met the requirements of loess soil hydraulic parameters suitable for plant growth. The five infiltration models well fitted the effects of the treatments of application pattern C and S1 particle size (R²>0.980), but the R² values of the Horton model exceeded 0.990 for all treatments (except for the treatment B2%_(S2)). Compared with CK, all other treatments reduced cumulative soil water infiltration, except for B4%_(S2). With the same application amount, cumulative soil water evaporation difference between application patterns A and B was small. Treatments of application pattern C and S1 particle size caused a larger reduction in cumulative soil water evaporation. The reductions in cumulative soil water evaporation under the treatments of C4%_(S1), C4%_(S2), C2%_(S1), and C2%_(S2) were over 15.00%. Therefore, applying 2% of mixed-based biochar with S1 particle size to the underlying layer (10-20 cm) could improve soil water infiltration while minimizing soil water evaporation. Moreover, application pattern was the main factor affecting soil water infiltration and evaporation. Further, there were interactions among the three influencing factors in the infiltration process (application amount×particle size with the most important interaction), while there were no interactions among them in the evaporation process. The results of this study could contribute to the rational application of mixed-based biochar in aeolian sandy soil and the resource utilization of urban and agricultural wastes in mining areas.